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| Titel |
Carbon sources in suspended particles and surface sediments from the Beaufort Sea revealed by molecular lipid biomarkers and compound-specific isotope analysis |
| VerfasserIn |
I. Tolosa, S. Fiorini, B. Gasser, J. Martin, J. C. Miquel |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 3 ; Nr. 10, no. 3 (2013-03-26), S.2061-2087 |
| Datensatznummer |
250018172
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| Publikation (Nr.) |
 copernicus.org/bg-10-2061-2013.pdf |
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| Zusammenfassung |
| Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids)
and compound-specific isotope analysis of suspended particulate organic
matter (SPM) and surface sediments of the Mackenzie Shelf and slope
(southeast Beaufort Sea, Arctic Ocean) were studied in summer 2009. The
concentrations of the molecular lipid markers, characteristic of known
organic matter sources, were grouped and used as proxies to evaluate the
relative importance of fresh algal, detrital algal, fossil, C3
terrestrial plants, bacterial and zooplankton material in the organic matter
(OM) of this area. Fossil and detrital algal contributions were the major
fractions of the freshwater SPM from the Mackenzie River with
~34% each of the total molecular biomarkers. Fresh algal,
C3 terrestrial, bacterial and zooplanktonic components represented much
lower percentages, 17, 10, 4 and <1%, respectively. In marine
SPM from the Mackenzie slope, the major contributions were fresh and
detrital algal components (>80%), with a minor contribution
of fossil and C3 terrestrial biomarkers. Characterization of the
sediments revealed a major sink of refractory algal material mixed with some
fresh algal material, fossil hydrocarbons and a small input of C3
terrestrial sources. In particular, the sediments from the shelf and at the
mouth of the Amundsen Gulf presented the highest contribution of detrital
algal material (60–75%), whereas those from the slope contained the
highest proportion of fossil (40%) and C3 terrestrial plant material
(10%). Overall, considering that the detrital algal material is marine
derived, autochthonous sources contributed more than allochthonous sources
to the OM lipid pool. Using the ratio of an allochthonous biomarker
(normalized to total organic carbon, TOC) found in the sediments to those
measured at the river mouth water, we estimated that the fraction of
terrestrial material preserved in the sediments accounted for 30–40% of
the total carbon in the inner shelf sediments, 17% in the outer shelf and
Amundsen Gulf and up to 25% in the slope sediments. These estimates are
low compared to other studies conducted 5–20 yr earlier, and they support
the increase in primary production during the last decade mainly because of
the increase in the number of ice-free days and due to the strength and
persistence of winds favouring upwelling. |
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